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Digital TV: Where to from here? What has been achieved since we asked this question back in March 2010? There has been a lot of change but in some ways, we’ve gone backwards! Alan Hughes reports . . . W e have moved from an upscaled version of the primary Standard Definition (SD) program on commercial TV’s High Definition (HD) channel (eg, OneHD, 7Mate or GEM) to independent programming between the primary and secondary independent programs in HD (eg, 11, 7Two or GO!) and another in SD with a third datacasting channel (eg, TVSN, 4ME, Gold). However not all programs on the HD channels are HD originals but are up-scaled SD programs. The ABC is now carrying 4 channels of programs but has transferred its HD service from the main channel, ABC1, to their 24-hour news channel, ABC24. SBS is still simulcasting SBS1 in HD and SD and has added SBS2 and NITV. Community TV stations (Logical Channel Number 44) are now all digital on UHF in five of the mainland state capitals. will be closed on 10th December this year. Change-over subsidises have been available for those areas covered by Aurora analog ground-based repeater receivers which will not be converted to digital. Low-band VHF All TV transmissions between 45 – 144 MHz (channels 0 – 5A) have now stopped with the exception of the Sydney and Melbourne main ABC transmitters. Even these analog transmitters will cease to transmit on 10th December this year. The 87.5-108MHz FM radio band is now completely clear of TV channels 3-5. Single Frequency Networks, where identical program is transmitted by more than one transmitter in the cov- erage area, has been introduced and extended. Currently they are used in Cairns, Sunshine Coast/Brisbane/Gold Coast, Toowoomba, Newcastle, NSW Central Coast, a pair in Sydney, the Dandenongs, eastern and western sides of Port Phillip Bay. After all, there are only four UHF channel blocks to choose from (as shown in Table 1)! You’re not getting full HD TV! The Department of Broadband, Communications and Digital Economy runs “Digital Tracker” surveys once per quarter. The fourth quarter 2012 survey reports that 92% of viewers can receive HD signals and around 83% of them can display that quality. VAST The “Viewer Accessed Satellite Television” (VAST) is now carrying, to remote areas of WA and black-spot areas, the same 18 programs as regional WA gets. The remote Queensland and Northern Territory gets 17 programs in Eastern Time and the balance of the country gets 16 programs in Eastern Daylight Time. There are also repeats of the regional news from each commercial region as well. This service uses the latest DVBS2 modulation and MPEG-4 compression for the HD channels. The older 4-program “Aurora” service which uses DVB-S and MPEG-2 36  Silicon Chip Relative signals levels including the shortening of the dipole with increasing channel number (not included in manufacturers’ specifications). The alphabet channels are used for the Wifi channels which are not wanted. siliconchip.com.au Summary: • • • • • • • • From the start of 2014 all primary channels need to be HD and the existing HD channels may become SD. MPEG4-capable receivers need to become standard. Analog TV finishes on December 10 2013. The restack (retuning) will be complete by December 10 2014. TV antennas which are wider than 750mm are still being sold and installed are not suitable for digital TV. TV antennas should be chosen according to the specific channel block for their site as well as the polarisation used. Block A band 3 VHF; Block B band 4 UHF; Blocks C-E channels 28 - 51 only. Once the restack is complete in your area there is no need for any dual-band VHF/UHF antennas. There are many dual-band Log Periodic antennas being promoted and sold at the moment. Only a small part of these antennas is being used. All antennas designed for “analog” or “analog and digital” should be taken off the market because their only use is to pick up analog ABC1 on channel 2 in Sydney and Melbourne which are simulcast in digital anyway. There are many antennas designed to include channel 52+. They are sensitive to interference from the new wireless data transmitters to start in 2015. Initially all HD signals had the potential of 1920 pixels/line and 1080 lines per viewable frame, sent in an interlaced fashion at 25 frames/second. However, now all but ABC24 transmit 1440 x 1080 x 25i, which means that the sharpness of vertical edges in the picture is reduced and diagonal lines and circles have jagged edges. All but the smallest TV screen sizes capable of receiving are full HD. (1920 x 1080 progressive scan order as mentioned above). But with the broadcasts being interlaced, only half the picture detail is updated at a time. Full HD is recorded onto Blu-ray discs by the movie manufacturers at 24 frames/second, so now the general public’s TVs can display sharper images via Blu-ray than the broadcasters transmit at their best! Compression systems These systems reduce the 829 Mbit/s of a full HD picture signal down to around 15Mbit/s for transmission. MPEG-2 (also called H262) is used throughout our TV broadcast system with the exception of VAST HD satellite transmission. MPEG-4 (also called H264 or MP4) was standardised six years ago. It produces half the data rate signal for the same image quality as compared to MPEG-2. MPEG-4 is used in most Blu-ray movies, in many countries, (with the exception of North America but including NZ) for broadcast TV, VAST HD and Foxtel HD. It was also used in Australia for the 3-D transmission of the Olympics, World Cup Soccer and Rugby League grand finals. MPEG-4 siliconchip.com.au was added to Australian Standard “4933.1 Digital television – Requirements for receivers” in 2010. Sony has stated publically that all its receivers from 2009 have been capable of MPEG-4 reception and virtually all Personal Video Recorders (PVRs) are also MPEG-4 capable. No other manufacturers have made any comment and the compression type is missing from nearly all manufacturers’ specifications. The number of capable receivers is unknown. What needs to be achieved by the end of this year? It is an ACMA requirement that real HD (not upscaled SD) has to be broadcast for 1040 hours per year (3 hours/day) by each broadcaster. But this requirement ends 10th December, the same time as the last analog TV signals cease. Considering that viewers have collectively invested a lot more money than the broadcasters in buying new full HD receivers, the broadcasters need to broadcast their most popular programs in HD, just as is done in the USA and the UK. We know that the audience is equipped to receive it so – ONE (using TEN’s programs), ABC1, SBS1, Southern Cross, Prime/GWN, Seven, WIN/NBN/Imparja and Nine should be switched to HD and the original ONE (to be called 10), ABC24, 7mate and GEM become SD. SBS1 in SD stops transmission. This means that the HD programs can be selected with a single button push on the remote control. The ability of the audience to re- ceive MPEG-4 needs to be determined. The DBCDE Digital Tracker surveys will only occur for the third and final quarters of this year. They could be used to determine the percentage of MPEG-4 capable receivers. This can be done by stopping the SBS1 simulcast in Adelaide, Perth and Brisbane and replacing SBS1 SD with an MPEG-4 compressed full HD signal containing an electronically moving square along with an identifying caption. This produces an image in which smooth motion can be seen – and the data required for such an image is small enough not to exceed the data rate for a normal SD program. This could also be transmitted on ABC3 between 9:01 PM and 06:00 AM (the time it is currently off-air) in SD. We are now getting video transmission rates of SD which are approaching sound data rates so we also need to test if receivers are capable of Advanced Audio Compression (AAC-V2) which could be tested at the same time. One on-line retailer is selling a Set Top Box/Recorder for $22 + $9 postage, while a chain store is selling a similar product of the shelf for $39. If all programs are transmitted in MPEG-4, a Personal Video Recorder will be able to record twice as much programming on its hard drive, as the transmission data rate has been halved. This survey could also be used to test if receivers can display Full HD pictures using progressive scanned signals and 24 frame/s video to give us movies without the increase in sound pitch and reduced length. June 2013  37 This six-element Yagi antenna has all its elements about the same length giving maximum sensitivity and directivity to a small range of channels. This VHF-only type would be typically used in most state capitals postDecember 10. What needs to be achieved by the near future? The www.digitalready.gov.au website uses propagation software to estimate the signal strength at any street address in Australia. It has been backed up by an ACMA physical signal strength survey. It has resulted in many new translator sites to fill in black spots. Most will require channel changes when the restack occurs for each site. DVB-T2 is a new modulation technique which doubles the data carrying capacity of a transmission channel over our present DVB-T system. It also allows rugged transmission to hand-held devices without paying a telecommunications company if a compatible demodulation integrated circuit is installed. This modulation technique is being used in the UK to carry five full HD programs on a single transmitter. These programs are MPEG-4 compressed. DVB-T2/MPEG-4 set top boxes are available overseas. Stereoscopic or 3-D TV compression standard H265 was standardised in January and produces a data stream a quarter of the size we currently use on air. Combined with the DVB-T2 dou- Restack channel blocks bling the transmission channel capacity, this gives enough data width to transmit full HD S-3D signals to all TVs. The S-3D signal consists of a standard two-dimensional signal along with a depth signal telling 3D TVs how far the object is away. Digital restack The digital restack has commenced and will be completed by the end of next year. It will be used to sell TV channels 52 – 69 to the wireless data industry for LTE data transmission. It is a process of moving all transmitters on a single site on to one of the channel blocks as shown in Table 1 below. A restack example on the main transmitter sites in the mainland state capital cities: SBS will start transmission on transmission channel 7 as soon as 7 analog has switched off and in Sydney and Melbourne’s case switch off their UHF digital transmitter three months later. This is to allow antenna installers time to retune or replace channel amplifiers in multi-dwelling units (MATV systems). All TVs will need to have a channel search done to find SBS’s new transmission channels. Viewers using translators will need to do a channel search on other dates. The implications on new receiving antennas of the restack is that there will be no need for VHF/UHF antennas or for cross-polarised antennas as used in Canberra, Goulburn Valley Vic, Manning River NSW, and Gladstone East Qld. Note that on top of this if you double the number of elements the gain only rises 3dB, so tuning the antenna to the block of six channels drastically improves antenna performance for the desired channels and rejects all other surrounding signals in frequency. Contrast this to a “log periodic” antenna designed for Australian channels 6 – 12, 20 – 75. One of these is shown opposite. AS1417.1(Int)-2011 “Receiving antennas for radio and television in the VHF and UHF broadcast bands” ran out on 24th February and is yet to be completed. It needs to ban the sale of any TV antenna designed for coverage of any frequency below 176MHz, the lower edge of our channel 6, and above 694MHz the upper edge of channel 51. (European channels 5 – 48). These antennas are still being installed as I write for transmissions which don’t (or shortly won’t) exist. Community TV (channel 44) Community TV (channel 44) in mainland state capitals transmits in Band 4, UHF. There has been no decision by the DBCDE/ACMA as to whether they will be restacked to transmission channel 10, or share with SBS to allow translators to operate in black holes in the coverage area such as CBD Sydney, Melbourne, Perth, Geelong, Kings Cross, Sydney’s northern beaches , the Dandenongs and the Adelaide hills as examples. Transmission channels for 2 government, 3 commercial and 1 unallocated (but will be used for community TV in some locations). Each transmitter site is allocated only one block of channels – the same polarisation will be used for all transmissions from that site. A (VHF) 6 7 8 10 11 12 B (UHF) 28 29 30 31 32 33 C (UHF) 34 35 36 37 38 39 D (UHF) 40 41 43 43 44 45 E (UHF) 46 47 48 49 50 51 Table 1: the ACMA restack block channel allocations. All transmitters have the same transmission characteristics. A 6MHz guard band above channel 51 is being used to prevent TV interfering with WiFi and vice-versa. Note: TV stations transmit a logical channel number such as channel 2 for ABC1, even if the receiver is physically tuned to any of the channels in the table. This transmission channel tuning occurs during installation or channel search. 38  Silicon Chip siliconchip.com.au  <at>: Wanted for digital reception : Wanted for digital reception but reduced in length <at> #: Not wanted for any digital reception *: Not required for most mainland state capital cities <at> <at> <at> <at> * * * * ** * * * * * * * * * # A currentlyavailable antenna for VHF channels 2-12 #and UHF channels 28-36. Most of the elements are wasted and indeed could # cause interference. # # Currently the only translator is for South Yarra (Melbourne) and has only a tiny power output. What needs to be achieved by the end of next year? We need to include now in Australian Standards 4933.1 “Digital television – Requirements for receivers and AS 4599.1-2011 Digital television – Terrestrial broadcasting – Characteristics of digital terrestrial television transmissions” a requirement for DVBT2 with AAC-V2 surround sound in all receivers from next year and for all the transmitters to be capable within five years. In addition, H.265 compression needs to be specified as soon as decompression integrated circuits become available. Note existing receivers cannot produce a viewable signal from a DVB-T2 signal and H265 decompressor will be combined with MPEG-4/MPEG-2 decompression integrated circuit. Software versions can be added to existing computers and phones. Lastly, the Australian Standards referred to above need to be made mandatory for manufacturers and importers to allow improvements for the minimum price, at the maximum WHEN IS THE BIG SWITCH? If TV in your area hasn’t yet changed and you’d like to know when it will and what to, visit: www.dbcde.gov.au/__data/assets/pdf_ file/0010/161011/Channel_change_timetable_for_Web_-_March_2013.pdf speed and without the need for subsidies. The ACMA has the ability to make Australian Standards mandatory. With the introduction of DVB-T2 modulation the TV transmission network will carry around 276Mbit/s of one-way simultaneous information flow. This is compared to the NBN (National Broadband Network) which has a maximum of 100Mbit/s per household, however the speed will depend on traffic, particularly if many viewers are watching the same program. DTV transmission is cheaper for many viewers watching the same program whereas the NBN is designed for View on Demand where the viewers are all watching different programs simultaneously. H265 and the use of non-frame compatible stereoscopic 3-D TV can be carried on terrestrial broadcast, fibre optic internet or satellite TV, which is in order of cost. We live in technically exciting times. Suppliers of TV equipment, antennas and the broadcasters themselves have been given adequate notice of switchover dates. SC Mainland State Capital City Area Translators   Adelaide  Perth  Brisbane  Sydney  Melbourne Adelaide Foothills (CH) Roleystone (DH) Boonah (DV) Bouddi (DEV) Ferntree Gully (DH) __ Angaston (CH) Lancelin (DH) Brisbane NW (DV) Gosford (DEH) Anglesea/Aireys Inlet (BH) _ Cape Jervis (DV) Mandurah/Singleton (BV) Brisbane SE (BV) Kings Cross (BH) Geelong (EH) _ Carrickalinga (EH) Perth City (EH) Canungra (BH) Manly/Mosman (BH) Healesville (CV) _ Craigmore/Hillbank (CV) Perth Coastal (EH) Currumbin (DV) Picton (DV) Marysville (CH) _ Elisabeth South (BV)* Toodyay (EH) Esk (CV) Sydney NW (BH) Melbourne inner suburbs (DV) _ Eudunda (CV) Two Rocks (B) Gold Coast (DEH) Sydney SW (DH) Monbulk (EV) _ Gumeracha (EH) Gold Coast South (CDH) Woronora (DV) Ocean Grove (DH) _ Lyndoch (CV) Kooralbyn (BV) Wyong (DEV) Rosebud (DV) _ Maitland (EV) Maroon (EH) Safety Beach (DH) _ Mannum (DH) Mount Alford (EV) Selby (CH) _ Myponga (DV) Rathdowney (BV) South Yarra (DV) _ Normanville (CV) Sunshine Coast Sth (CH) Upwey (CV) _ Strathalbyn (DV) Warburton (CH) _ Swan Reach (CH) Wye River (CV) _ First letter(s) in parentheses are block used. Last letter is polarisation – horizontal or vertical Victor Harbour (CV) _ * No commercials or community TV on this site Italics may be a new site Yankalilla (DH) siliconchip.com.au June 2013  39